CN115307538A - Angular position sensor system - Google Patents

Abstract

An angular position sensor system comprising: a two-pole magnet rotatable about a rotation axis; a magnetic sensor device including a plurality of horizontal hall elements including at least a first horizontal hall element, a second horizontal hall element, and a third horizontal hall element located on a virtual circle having a center located on a rotation axis; the Hall elements are spaced apart by multiples of 90 °; wherein the magnetic sensor device further comprises a processing unit connected to the horizontal hall elements for obtaining the first, second and third signals (h 1, h2, h 3) and for determining a first pair-wise difference (d 1) between the first and second sensor signals (h 1, h 2) and for determining a second pair-wise difference (d 2) between the second and third sensor signals (h 2, h 3) and for determining an angular position (θ) of the magnet relative to the sensor device based on a ratio of these pair-wise differences (d 1, d 2).

Description

Angular position sensor system

Technical Field

The present invention relates generally to angular position sensor systems having two-pole magnets and having a 360 measurement range.

Background

Angular position sensor systems are known in the art. In such systems, a non-uniform magnetic field is typically generated (e.g., by electrostatic current or by permanent magnets) and measured by a sensor device that includes one or more sensors and includes readout circuitry and a processor that calculates an angular position based on the measured values.

Various sensor systems and techniques for determining angular position are known in the art, each having advantages and disadvantages such as cost, compactness, angular range, accuracy (e.g., signal-to-noise ratio, SNR), signal sensitivity, robustness to unwanted external fields (stray fields), robustness to position errors (e.g., due to axial and/or radial offset of the sensor relative to the magnet), processing complexity, redundancy (e.g., error detection capability, error correction capability), etc.

WO98/54547 describes a magnetic rotation sensor system comprising a two-pole magnet and a sensor device with four hall elements.

There is always room for improvement and replacement.

Disclosure of Invention

It is an object of embodiments of the present invention to provide an angular position sensor system suitable for automotive applications.

It is an object of an embodiment of the present invention to provide an angular position sensor system, comprising: two-pole magnet and sensor device, wherein the sensor device is movable relative to the magnet or vice versa and is capable of measuring the angular position of the sensor device relative to the magnet over a 360 ° range.

It is an aim of embodiments of the present invention to provide an angular position sensor system in which the sensor device comprises a relatively small number (or reduced number) of magnetic sensor elements (e.g. only three magnetic sensor elements).

It is an object of embodiments of the present invention to provide an angular position sensor system that is highly insensitive to external disturbing fields and/or to aging effects and/or to demagnetization effects, preferably all of these.

It is an aim of embodiments of the present invention to provide an angular position sensor system having error detection capability (e.g. capable of detecting that one of the sensor elements is defective).

It is an aim of embodiments of the present invention to provide an angular position sensor system having error correction capability (e.g. capable of providing a correct angular position even if one of the sensor elements is defective).

It is an object of embodiments of the present invention to provide an angular position sensor system that is more compact (e.g., requires a smaller semiconductor substrate) without degrading accuracy (e.g., in terms of signal-to-noise ratio, SNR).

It is an aim of embodiments of the present invention to provide an angular position sensor system in which the angle is calculated in a relatively simple manner (e.g. without the need for a discrete fourier transform).

It is an object of embodiments of the present invention to provide an angular position sensor system suitable for functional safety applications.

It is an object of a preferred embodiment of the present invention to provide an angular position sensor system having at least two or at least three of the following features: reduced number of magnetic sensor elements, 360 ° range, robustness to external interference fields, error detection capability, error correction capability, compact sensor device.

These and other objects are achieved by a position sensor system and a method according to embodiments of the present invention.

According to a first aspect, the present invention provides an angular position sensor system comprising: a two-pole magnet rotatable about a rotation axis; a magnetic sensor device including a plurality of horizontal hall elements including at least a first horizontal hall element, a second horizontal hall element, and a third horizontal hall element located on a virtual circle, the circle having a center located on a rotation axis; wherein the first and second horizontal hall elements are angularly spaced apart by 90 °, and wherein the first and third horizontal hall elements are angularly spaced apart by 180 °; wherein the magnetic sensor device further comprises a processing unit connected to the first, second and third horizontal hall elements for obtaining the first, second and third signals, and configured for determining a first pair-wise difference between the first and second sensor signals, and for determining a second pair-wise difference between the second and third sensor signals, and for determining an angular position of the magnetic sensor device relative to the magnet based on a ratio of the first and second pair-wise differences (e.g. arctangent or arctangent as the ratio).

Advantageously, the angular position sensor system has a 360 ° range.

Advantageously, the angle thus determined is highly insensitive to external disturbing fields (thanks to the signal difference) and to the mounting distance between the sensor device and the magnet (thanks to the ratio).

Advantageously, only three horizontal hall elements are required to determine the angular position. Depending on the implementation, this allows for example a faster readout (since only three sensor elements need to be read), and/or a simpler circuitry.

The magnets may be axially or diametrically magnetized bipolar ring or disk magnets.

The first, second and third horizontal hall elements are preferably integrated in a single semiconductor substrate.

Advantageously, the sensor device does not comprise a flux concentrator (also referred to as "integrated magnetic concentrator", IMC). This requires fewer processing steps during production of the sensor device and may reduce lifetime problems (e.g. due to delamination effects).

Preferably, each of the horizontal hall elements has a maximum sensitivity axis parallel to the rotation axis.

The processing unit may be adapted to calculate said relative position according to the following formula: θ = arctan (R), wherein R = DIFF1/DIFF2, and wherein DIFF1= (h 1-h 2) or DIFF1= (h 2-h 1), and wherein DIFF2= (h 3-h 2) or DIFF2= (h 2-h 3), wherein h1 is the first sensor signal, h2 is the second sensor signal, and h3 is the third sensor signal.

In an embodiment, the imaginary circle (imaginary circle) has a radius R1, and the horizontal hall element is integrated on a semiconductor substrate having an area smaller than four times the square of the radius.

An advantage of the sensor device is that the three sensor elements lie on a circle having a radius R, while the semiconductor substrate has an area of less than 4 × R, which is the area of the smallest square containing the entire circle. This allows the size of the semiconductor substrate to be reduced without reducing the radius.

In an embodiment, the sensor device comprises only three horizontal hall elements.

Advantageously, such a sensor device requires a smaller number of components, thus reducing the risk of defective components.

In an embodiment, the plurality of horizontal hall elements further comprises a fourth horizontal hall element located on said imaginary circle and spaced 180 ° apart from the second horizontal hall element, and wherein the processing unit is further connected to the fourth horizontal hall element to receive a fourth sensor signal; and wherein the processing unit is further configured for one or more or all of: i) Determining a third pair-wise difference between the third sensor signal and the fourth sensor signal, and for determining a second angle of the magnetic sensor device based on a ratio of the second pair-wise difference and the third pair-wise difference; ii) determining a third pair-wise difference between the third sensor signal and the fourth sensor signal, and determining a fourth pair-wise difference between the first sensor signal and the fourth sensor signal, and for determining a third angle of the magnetic sensor device based on a ratio of the third pair-wise difference and the fourth pair-wise difference; iii) A fourth pair of differences (between the first sensor signal and the fourth sensor signal) is determined, and a fourth angle for the magnetic sensor device is determined based on a ratio of the fourth pair of differences and the first pair of differences.

Advantageously, such a sensor device may use different combinations of only three sensors to determine more than one angular position. This provides redundancy that can be used for fault detection.

In practice, two or more of these angles may be compared and if the values of these angles deviate by less than a predefined value, it may be concluded that all sensor elements are working correctly. In this case, two or three or all angles may be averaged, thereby achieving improved accuracy.

Thus, the comparison of the angles allows at least error detection, but if the device is also able to find out which sensor element is not working correctly, it even allows error correction by using angles based on three correctly working hall elements.

In an embodiment, which sensor element is defective is determined based on analyzing four difference signals d12= (h 1-h 2), d23= (h 2-h 3), d34= (h 3-h 4), and d41= (h 4-h 1), which should be 90 ° phase shifted if all sensor elements are working correctly. For example, if h4 is defective, d12 and d23 will be phase shifted by 90 °, but d23 and d34 will typically not be phase shifted by 90 °, d34 and d41 will typically not be phase shifted by 90 °, and d41 and d12 will typically not be phase shifted by 90 °. Thus, by which of the test signals d12, d23, d34 and d41 is phase shifted by 90 °, it can be determined which sensor element is defective.

In an embodiment, the processing unit is further configured for determining a first diagonal difference being a difference between the first signal and the third signal, and for determining a second diagonal difference being a difference between the second signal and the fourth signal, and for determining the fifth angle of the magnetic sensor device based on a ratio of these diagonal differences.

In this embodiment, the fifth angle is determined in the same manner as shown in fig. 1 (c). This fifth angle has an improved signal-to-noise ratio. Thus, in this embodiment, the advantages of FIG. 1 are combined with the error detection and/or error correction capabilities of FIG. 3 (b).

In an embodiment, the plurality of horizontal hall elements further includes a fourth horizontal hall element, a fifth horizontal hall element, and a sixth horizontal hall element located on a second virtual circle, the second circle having a second center located on the rotation axis; and wherein the processing unit is further connected to the fourth, fifth and sixth horizontal hall elements and is further configured for receiving the fourth, fifth and sixth sensor signals; and wherein the processing unit is further configured for determining a first additional pair-wise difference between the fourth sensor signal and the fifth sensor signal, and for determining a second additional pair-wise difference between the fifth sensor signal and the sixth sensor signal, and for determining an additional angle of the magnetic sensor device with respect to the magnet based on a ratio of the first additional pair-wise difference and the second additional pair-wise difference.

The advantage of this embodiment is that the first, second and third horizontal hall elements can be used as a first set of three sensors and the first angular position can be calculated based on signals obtained from the first set of sensors; the fourth, fifth, and sixth horizontal hall elements may function as a second set of three sensors, and the second angular position may be calculated, independently of the first set, based on signals obtained from the second set of sensors. Thus, the first set may be used as a primary set and the second set may be used as a redundant set, e.g. for error detection.

Depending on the implementation, the precision of the second angle obtained from the second set may be equal to or less than the precision of the first angle obtained from the first set.

The processing unit may further be adapted to compare the first angle and the second angle and to detect an error if the first angle and the second angle deviate by more than a certain threshold value and to output a result of the comparison. Alternatively or additionally, the processing unit may be configured to output the two angle values to allow an external processor to make the comparison.

In an embodiment, the first circle has a first radius (R1) and the second circle has a second radius (R2) equal to the first radius (R1).

In an embodiment, the first circle has a first radius (R1) and the second circle has a second radius (R2) smaller than the first radius (R1).

In an embodiment, the fourth and fifth horizontal hall elements are angularly spaced apart by an angle in a range of 80 ° to 89 ° or 91 ° to 100 °, and wherein the fifth and sixth horizontal hall elements are angularly spaced apart by an angle in a range of 80 ° to 89 ° or 91 ° to 100 °.

An example of this embodiment is shown in fig. 4 (b). An advantage of this embodiment is that all horizontal hall elements are located on a single imaginary circle, thus providing substantially the same signal amplitude. The second and fifth horizontal hall elements may be angularly spaced by 180 °, in which case a "diagonal difference" (h 2-h 5) may also be calculated (e.g., in the event that no error is detected), the first and second angles being offset from each other by 180 °.

In this case, the first set of sensor elements may be positioned on a "first portion" of the semiconductor substrate and the second set of sensor elements may be positioned on a "second portion" of the semiconductor substrate, the second portion not overlapping the first portion, e.g., as shown in fig. 4 (e).

In an embodiment, the sensor elements of the first set and their biasing and sensing circuits are galvanically separated from the sensor elements of the second set and their biasing and sensing circuits. In this embodiment, at least the "first part" has a processing unit inside the device. Optionally, the second part also has a second processing unit inside the device, but this is not absolutely necessary. Alternatively or additionally, the second part is configured to output (preferably in digital format after analog-to-digital conversion) the measurement values and/or the pair-wise differences to allow the external processor to perform a consistency check.

In an embodiment, the fourth and fifth horizontal hall elements are spaced apart by 90 °, and the fifth and sixth horizontal hall elements are also spaced apart by 90 °, i.e. the fourth and sixth elements are spaced apart by 180 °.

An example of this embodiment is shown in fig. 4 (c), where the sixth hall element is located "between" the first hall element and the second hall element (on an arc).

An advantage of this embodiment is that both the first angle and the second angle can be calculated using a simple arctangent of the ratio of the two difference signals, and the second angle can also be calculated using a simple arctangent of the ratio of the two difference signals. This embodiment is also advantageous in that the two angles can be calculated with the same accuracy.

In an embodiment, the first virtual circle has a first radius R1 and the second virtual circle has a second radius R2 smaller than the first radius R1; and the first, third, fourth and sixth horizontal hall elements are collinear.

In this embodiment, the processor unit may be further configured to test whether the signals (h 1-h 3) are proportional to (h 6-h 4) to detect an error.

In an embodiment, the first virtual circle has a first radius R1 and the second virtual circle has a second radius R2 equal to or smaller than the first radius R1; and a distance between a center of the first hall element and a center of the fourth hall element is less than 250 μm; and a distance between a center of the second hall element and a center of the fifth hall element is less than 250 μm; and a distance between a center of the third hall element and a center of the sixth hall element is less than 250 μm.

In embodiments, these distances are less than 200 μm, or less than 150 μm, or less than 100 μm, or less than 50 μm.

An example of this embodiment is shown in fig. 4 (d) and 5 (b). By arranging the sensor elements relatively close together, the semiconductor substrate may be more compact and/or signals from closely spaced sensor elements may be combined (e.g., connected in parallel or series).

In an embodiment, the semiconductor substrate has an area in the range of 51% to 98% of 4 x (R1) or in the range of 51% to 95% of 4 x (R1) or in the range of 55% to 90% of 4 x (R1) or in the range of 55% to 80% of 4 x (R1) wherein R1 is the radius of the (first) imaginary circle.

Such an implementation provides redundancy while requiring less space (more compact and less expensive), which is a major advantage.

In an embodiment, the processor unit is configured for outputting at least two angular values (e.g. θ 1, θ 2), and wherein the angular position sensor system further comprises an Electronic Control Unit (ECU) communicatively connected to the magnetic sensor device, and configured for receiving the at least two angular values, and further configured for detecting the error based on a comparison of the first angular value and the second angular value.

In this embodiment, the processing unit determines two angles and optionally compares the two angles, and the external processing unit receives the two angles and also compares the two angles.

Optionally, the electronic control unit may be further adapted to add or subtract a predefined offset to or from the second angular value before comparing the first and second angular values.

In an embodiment, the processor unit is configured for outputting at least a first angular value (e.g. θ 1) and at least two difference signals; and the angular position sensor system further comprises an Electronic Control Unit (ECU) communicatively connected to the magnetic sensor device; and the Electronic Control Unit (ECU) is configured for receiving the first angular value (e.g. θ 1) and the at least two difference values, and further configured for calculating a second angular value (e.g. θ 2) based on these difference values, and for detecting an error based on a comparison of the first and second angular values (θ 1, θ 2).

Optionally, the electronic control unit may be further adapted to add or subtract a predefined offset to or from the second angular value before comparing the first and second angular values.

In an embodiment, the plurality of horizontal hall elements further comprises a fourth horizontal hall element (e.g., H4) located on the imaginary circle and spaced 180 ° apart from the second horizontal hall element (e.g., H2), and the processing unit is further connected to the fourth horizontal hall element to receive a fourth sensor signal (e.g., H4); and the processing unit is further configured for determining a first diagonal difference (e.g. dd 1) as the difference between the first signal (e.g. h 1) and the third signal (e.g. h 3) and for determining a second diagonal difference (e.g. dd 2) as the difference between the second signal (e.g. h 2) and the fourth signal (e.g. h 4) and optionally for determining a second angle (e.g. θ 5) of the magnetic sensor device based on the ratio of these diagonal differences; and wherein the sensor device is further configured for outputting the angular position (e.g., θ) derived from the first, second and third horizontal hall elements as a first angle, and outputting at least one of the first and second diagonal differences (e.g., dd1, dd 2) and the second angle (e.g., θ 5).

In an embodiment, the sensor device is configured for determining said second angle (e.g. θ 5), and for performing a conformance test between said first angle (e.g. θ) derived from only three horizontal hall elements and said second angle (e.g. θ 5) derived from a diagonal difference, and for outputting a result of the conformance test.

In an embodiment, the system further comprises an electronic control unit (e.g. ECU) communicatively connected to the magnetic sensor device; and the electronic control unit (e.g., ECU) is configured to receive the first angular value (e.g., θ) and the second angular value (e.g., θ 5) and detect an error based on a comparison of the first angular value and the second angular value (e.g., θ 5).

In an embodiment, the system further comprises an electronic control unit (e.g. ECU) communicatively connected to the magnetic sensor device; and the electronic control unit (e.g. ECU) is configured for receiving a first angular value (e.g. θ) derived from only three horizontal hall elements, and for receiving a first and a second diagonal difference (e.g. dd1, dd 2), and for calculating a second angle (e.g. θ 5) based on the first and second diagonal differences, and for detecting an error based on a comparison of the first and second angular values (e.g. θ, θ 5).

Particular and preferred aspects of the invention are set out in the accompanying independent and dependent claims. Features from the dependent claims may be combined with features of the independent claims and with features of other dependent claims as appropriate and not merely as explicitly set out in the claims. These and other aspects of the invention will be apparent from and elucidated with reference to the embodiment(s) described hereinafter.

Drawings

Fig. 1 (a) and 1 (b) show an example of a magnetic position sensor system comprising a two-pole magnet and a magnetic sensor device having four horizontal hall elements spaced 90 ° apart on a notional circle.

Fig. 1 (c) shows how the angular position of the sensor device can be determined using an arctangent function of the ratio of two difference signals (referred to herein as "diameter difference signals") calculated between diametrically opposed elements.

Fig. 1 (d) shows an illustrative waveform of a signal as a function of angular position obtained from four hall elements using an arbitrary ratio, in the absence of an external disturbing field.

FIG. 1 (e) shows illustrative waveforms for two "diagonal difference signals," and shows the arctangent of the ratio of these signals to the angular position.

Fig. 2 (a) shows a magnetic sensor system comprising a two-pole magnet and a magnetic sensor device having only three horizontal hall elements spaced 90 ° apart on a phantom circle, which can be seen as a variant of the sensor arrangement shown in fig. 1 (b).

Fig. 2 (b) shows how a difference signal between adjacent hall elements can be calculated (referred to herein as an "adjacent difference signal" rather than a "diameter difference signal").

Fig. 2 (c) shows illustrative waveforms of two "adjacent difference signals" and shows the arctangent of the ratio of these signals to the angular position.

Fig. 2 (d), 2 (e) and 2 (f) are schematic diagrams showing examples of a semiconductor substrate including three horizontal hall elements arranged as in fig. 2 (a) or similar to fig. 1 (a).

Fig. 3 (a) shows a magnetic sensor system comprising a two-pole magnet and a magnetic sensor device having four horizontal hall elements spaced 90 ° apart on a phantom circle, similar to fig. 1 (b), but the signals obtained from these hall elements are or may be processed differently.

Fig. 3 (b) shows four methods of calculating angular position, each using a different subset of only three of the four sensor signals.

Fig. 4 (a) shows a magnetic sensor device that is a variation of the device of fig. 2 (e) having two discrete sets of three hall elements each, allowing two angles to be calculated independently, which can then be compared (internally or externally) for functional safety.

Fig. 4 (b) shows an illustrative arrangement of six sensor elements, where a first set of elements are spaced apart by a multiple of 90 °, and where a second set of elements are spaced apart by less than 90 ° (e.g., a value in the range of 80 ° to 89 °). The sensor elements of the first and second sets are not staggered.

Fig. 4 (c) shows an illustrative arrangement of six sensor elements, where the elements of the first set are spaced apart by multiples of 90 °, and where the elements of the second set are also spaced apart by 90 °, but where none of the elements of the first set coincide with elements of the second set. The sensor elements of the first and second sets are interleaved.

Fig. 4 (d) shows an example of a semiconductor substrate comprising two sets of three horizontal hall elements, which are arranged in a more compact manner than the arrangement of fig. 4 (c).

Fig. 4 (e) shows a sensor device using the same sensor topology as shown in fig. 4 (a), but wherein the sensor device contains two galvanic separation circuits, each comprising a set of three hall elements, biasing circuitry and readout circuitry.

Fig. 5 (a) shows a magnetic sensor device which is another variant of the device of fig. 2 (e), or of the device of fig. 4 (a), having a first set of three hall elements located on a first circle, and a second set of three hall elements located on a second circle, allowing two angles to be calculated independently, which can be compared (internally or externally) for functional safety.

Fig. 5 (b) shows an example of a semiconductor substrate including two sets of three horizontal hall elements each, arranged in a more compact manner than fig. 5 (a).

Fig. 6-8 show electrical block diagrams of circuitry that may be used in the position sensor apparatus described above.

Fig. 9 (a) to 9 (c) show several circuit topologies that may be used for reading out and optionally processing the signals provided by the two sets of magnetic sensor elements.

The drawings are only schematic and are non-limiting. In the drawings, the size of some of the elements may be exaggerated and not drawn on scale for illustrative purposes. Any reference signs in the claims shall not be construed as limiting the scope. The same reference numbers in different drawings identify the same or similar elements.

Detailed Description

The present invention will be described with respect to particular embodiments and with reference to certain drawings but the invention is not limited thereto but only by the claims. The drawings described are only schematic and are non-limiting. In the drawings, the size of some of the elements may be exaggerated and not drawn on scale for illustrative purposes. The dimensions and relative dimensions do not correspond to actual reductions to practice of the invention.

Moreover, the terms first, second, and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a sequential order temporally, spatially, in ranking, or in any other manner. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other sequences than described or illustrated herein.

Furthermore, the terms top, bottom, and the like in the description and the claims are used for descriptive purposes and not necessarily for describing relative positions. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other orientations than described or illustrated herein.

It is to be noticed that the term 'comprising', used in the claims, should not be interpreted as being restricted to the means listed thereafter; it does not exclude other elements or steps. Accordingly, the terms are to be interpreted as specifying the presence of the stated features, integers, steps or components as referred to, but do not preclude the presence or addition of one or more other features, integers, steps or components, or groups thereof. Thus, the scope of the expression "a device comprising means a and B" should not be limited to devices consisting of only components a and B. It means that for the present invention, the only relevant components of the device are a and B.

Reference throughout this specification to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment, but may. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments as would be apparent to one of ordinary skill in the art in view of this disclosure.

Similarly, it should be appreciated that in the description of exemplary embodiments of the invention, various features of the invention are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure and aiding in the understanding of one or more of the various inventive aspects. This method of disclosure, however, is not to be interpreted as reflecting an intention that the claimed invention requires more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive aspects lie in less than all features of a single foregoing disclosed embodiment. Thus, the claims following the detailed description are hereby expressly incorporated into this detailed description, with each claim standing on its own as a separate embodiment of this invention.

Furthermore, although some embodiments described herein include some but not other features included in other embodiments, combinations of features of different embodiments are intended to be within the scope of the invention and form different embodiments, as will be understood by those skilled in the art. For example, in the appended claims, any of the claimed embodiments can be used in any combination.

In the description provided herein, numerous specific details are set forth. However, it is understood that embodiments of the invention may be practiced without these specific details. In other instances, well-known methods, structures and techniques have not been shown in detail in order not to obscure an understanding of this description.

The invention relates to an angular position sensor system comprising a two-pole magnet and a sensor device, wherein the magnet is rotatable relative to the sensor device and vice versa. For convenience of description, the present invention will be explained on the assumption that the sensor device is stationary and the magnet is rotatable about the rotation axis, but the present invention is not limited thereto.

In this document, the hall elements H1, H2, etc. are generally indicated by upper case letters, and the signals H1, H2, etc. provided by these hall elements are generally indicated by lower case letters. Unless otherwise specifically noted, H1 is the signal provided by H1, H2 is the signal provided by H2, and so on.

In this document, the vertical axis of most graphs containing waveforms is shown in arbitrary units.

Fig. 1 (a) shows an example of an angular position sensor system 100, the angular position sensor system 100 comprising a two-pole magnet 110 and a magnetic sensor device 120, the magnetic sensor device 120 having four horizontal hall elements H1, H2, H3, H4, located on an imaginary circle (not shown) and angularly spaced apart by multiples of 90 °.

The magnet 110 may be a diametrically (diametrically) magnetized ring or disc magnet, or an axially magnetized ring or disc magnet.

The sensor device 120 comprises a semiconductor substrate and the horizontal hall elements H1, H2, H3, H4 are preferably integrated in the substrate. The substrate shown in fig. 1 (a) has a square shape. The coordinate system X, Y, Z is connected to the substrate. The X and Y axes are parallel to the substrate. The Z axis is perpendicular to the substrate and coincides with the axis of rotation of the magnet. The center of the imaginary circle is located on the rotation axis. In fig. 1 (a), the U-axis and the V-axis are also shown. They also lie in the X-Y plane and are rotated 45 deg. with respect to the X and Y axes.

The hall element H1 measures a magnetic field component Bz1 oriented parallel to the Z axis and provides a signal H1. The hall element H2 measures a magnetic field component Bz2 oriented parallel to the Z axis and provides a signal H2, etc. The sensor device 120 further includes a biasing circuit, a readout circuit, and a processing circuit for calculating the angular position. Such circuits are well known in the art and need not be explained in more detail here. For completeness, illustrative examples will be described in fig. 6-8.

As is known in the art (e.g. from WO 98/54547), the angular position θ m of the magnet 110 relative to the sensor apparatus 120 can be calculated as: θ m = arctan ((h 1-h 3)/(h 2-h 4)).

Fig. 1 (b) shows a sensor system 150 with a slightly different sensor device 170. It can be seen that in the sensor device 120 of FIG. 1 (a), the horizontal Hall elements H1-H4 are located on the diagonal of the square, while in the sensor device of FIG. 1 (b), the horizontal Hall elements H1-H4 are located near the middle of the sides of the square.

If the semiconductor substrates of fig. 1 (a) and 1 (b) are the same size, the hall element of fig. 1 (a) will generally provide a greater signal h1-h4 than the hall element of fig. 1 (b) because the hall element of fig. 1 (a) is located further from the center, and therefore the accuracy of the sensor device of fig. 1 (a) is generally better than the accuracy of fig. 1 (b). Or in other words, if the accuracy of the systems of fig. 1 (a) and 1 (b) is the same, the size of the semiconductor substrate 120 of fig. 1 (a) may be smaller than the size of the semiconductor substrate 170 of fig. 1 (b), and thus a packaged device ("integrated chip") including the semiconductor substrate of fig. 1 (a) may be smaller, more compact, and less expensive. Apart from size and accuracy, the solutions of fig. 1 (a) and 1 (b) are equivalent.

Fig. 1 (c) shows how the arc tangent function of the ratio of two difference signals d1, d2 measured between diametrically opposed elements can be used to determine the angular position θ m of the magnet 110 relative to the sensor device. These difference signals are referred to herein as "diameter difference signals".

Fig. 1 (d) shows illustrative waveforms of signals H1, H2, H3, H4 obtained from four hall elements H1, H2, H3, H4 without an external disturbing field. It can be seen that ideally the signals have the same amplitude but are phase shifted by 90 °. Thus, ideally, signals h1 and h3 have the same amplitude but opposite sign, and signals h2 and h4 have the same amplitude but opposite sign, so by subtracting them, the amplitude is doubled.

Fig. 1 (e) shows illustrative waveforms of two "diagonal difference signals" d1= (h 1-h 3) and d2= (h 2-h 4), and shows the arctangents of the ratios of these signals. It can be seen that signal d1 has twice the amplitude of signal h1, signal d2 has twice the amplitude of signal h2, and signals d1, d2 are 90 ° phase shifted.

Fig. 2 (a) shows a magnetic sensor system 200, which magnetic sensor system 200 comprises a two-pole magnet 210 and a magnetic sensor device 220, which magnetic sensor device 220 has only three horizontal hall elements H1, H2, H3 which lie on an imaginary circle and are spaced apart from one another by 90 °. From a hardware perspective, the sensor system 200 can be viewed as a variation of the sensor system 150 shown in fig. 1 (b).

As mentioned above, the magnet 210 may be a diametrically magnetized ring or disk magnet, or an axially magnetized ring or disk magnet.

According to the basic idea of the present invention, the inventors have arrived at an idea of calculating difference signals d1, d2 between signals obtained from adjacent hall elements, as shown in fig. 2 (b). These difference signals d1= (h 1-h 2) and d2= (h 2-h 3) are referred to herein as "adjacent difference signals" rather than "diameter difference signals". The inventors have surprisingly found that "adjacent difference signals" have the same amplitude and are 90 ° phase shifted and therefore are quadrature signals. This is unexpected.

Fig. 2 (c) shows illustrative waveforms of the two "adjacent difference signals" d1, d2 and shows the arctangent of the ratio of these signals. The advantage is that the "adjacent difference signal" is not sensitive to the external disturbing field height, and thus the angle θ m derived therefrom is not sensitive to the external disturbing field height. The angle θ m can be calculated as: θ m = arctan [ (h 1-h 2)/(h 2-h 3) ], which can also be written (using a two-parameter arctangent function): θ m = atan2[ (h 1-h 2), (h 2-h 3) ].

Fig. 2 (d), 2 (e), and 2 (f) are schematic views showing examples of a rectangular semiconductor substrate including only three horizontal hall elements located on an imaginary circle and spaced apart by 90 °. Assuming that the radius of the imaginary circle is R, the semiconductor substrate of fig. 2 (d) is preferably about 2% to 20% greater than (2r × R); the semiconductor substrate of fig. 2 (e) is preferably 2% to 20% larger than (√ 2R); and the semiconductor substrate of fig. 2 (d) is preferably 2% to 20% larger than (2r × 2r). It will be appreciated that the semiconductor substrate of fig. 2 (f) has the same dimensions as the semiconductor substrate of fig. 1 (b), but that the semiconductor substrate of fig. 2 (d) and 2 (e) is much smaller, e.g. at least 10% or at least 20% or at least 30% smaller, while providing the same functionality of being able to measure angular position in a robust manner to external disturbing fields.

Fig. 3 (a) shows a magnetic sensor system 300, the magnetic sensor system 300 comprising a two-pole magnet 310 and a magnetic sensor device 320, the magnetic sensor device 320 having four horizontal hall elements spaced 90 ° apart on an imaginary circle, similar to fig. 1 (b), but the signals h1, h2, h3, h4 obtained from these hall elements are processed differently. The magnet 310 may be a diametrically magnetized ring or disk magnet, or an axially magnetized ring or disk magnet.

Fig. 3 (b) shows four methods of calculating angular position, each using a different subset of only three signals selected from the available four signals h1, h2, h3, h4.

The first angular position θ 1 may be calculated using the signals H1, H2, H3 obtained from the sensor elements H1, H2, H3, instead of using the signal H4 obtained from H4, for example, according to the following formula: θ 1= atan2[ (h 1-h 2), (h 2-h 3) ].

Instead of using the signal H1 obtained from H1, the second angular position θ 2 can be calculated using the signals H2, H3, H4 obtained from the sensor elements H2, H3, H4, for example according to the following formula: θ 2= atan2[ (h 2-h 3), (h 3-h 4) ].

The third angular position θ 3 may be calculated using the signals H1, H3, H4 obtained from the sensor elements H1, H3, H4, instead of using the signal H2 obtained from H2, for example, according to the following formula: θ 3= atan2[ (h 3-h 4), (h 4-h 1) ].

The fourth angular position θ 4 may be calculated using the signals H1, H2, H4 obtained from the sensor elements H1, H2, H4, instead of using the signal H3 obtained from H3, for example, according to the following formula: θ 4= atan2[ (h 4-h 1), (h 1-h 2) ].

To correspond to the mechanical angular position θ m, an associated offset may typically be added or subtracted from each angular value. For example, θ m = (θ 1-offset 1) = (θ 2-offset 2) = (θ 3-offset 3) = (θ 4-offset 4), where offset 1 to offset 4 are predefined values. In the example, the offset 1=0 °, the offset 2=90 °, the offset 3=180 °, the offset 4=270 °, but other values may also be used. The predefined offset value may be hard coded or may be determined during calibration and stored in a non-volatile memory of the sensor device. Values of θ 1oc = (θ 1-offset 1), θ 2oc = (θ 2-offset 2) may be referred to as "offset compensation values" which should ideally be the same if all sensors are operating correctly.

In an embodiment, the sensor apparatus 320 calculates at least two of the four offset compensation values θ 1oc, θ 2oc, θ 3oc, θ 4oc and compares these values and outputs a signal indicative of the consistency or correspondence or correctness of the results, or a signal indicative of inconsistency or error or malfunction. For example, if at least two offset compensation values are found to deviate by less than a predefined amount (e.g., less than 5 °, less than 2 °, or less than 1 °), which may be hard coded, or may be configurable or programmable, the sensor device will decide that no fault has been detected. As a result, the sensor device may provide any one of the angular values θ 1, θ 2, θ 3, θ 4, or any one of the offset compensation values θ 1oc, θ 2oc, θ 3oc, θ 4oc, or an average or median value. The main advantage of the sensor device 320 is the ability to detect errors.

The offset compensation and/or comparison may also be performed outside the sensor device, for example in another processor connected to the sensor device.

The inventors have further realized that it is possible to detect not only errors, such as defective hall elements, but also which hall signal is incorrect and provide an angular position that does not use the signal from a defective hall element.

In an embodiment, the determination of which sensor element is defective is based on an analysis of four difference signals (h 1-h 2), (h 2-h 3), (h 3-h 4) and (h 4-h 1), which should have sample amplitudes and be phase shifted by 90 ° from each other if all sensor elements are working correctly, as shown in fig. 2 (c) for two of the difference signals.

For example, if the fourth hall element H4 is defective, d1= (H1-H2) and d2= (H2-H3) will still be 90 ° phase shifted (at any angular position), but d2= (H2-H3) and d3= (H3-H4) will typically not be 90 ° phase shifted, d3= (H3-H4) and d4= (H4-H1) will typically not be 90 ° phase shifted, and d4= (H4-H1) and d1= (H1-H2) will typically not be 90 ° phase shifted. Thus, if d1 and d2 are found to be 90 ° phase shifted, but d2 and d3 are not 90 ° phase shifted, and/or d3 and d4 are not 90 ° phase shifted, and/or d4 and d1 are not 90 ° phase shifted, the sensor device may output the correct angular position θ 1oc, and may additionally output that an error has occurred, or more specifically, that H4 may be defective (in this example).

Similarly, if it is found (in any angular position) that d2 and d3 are 90 ° phase shifted, while d3 and d4 are not 90 ° phase shifted, and/or d4 and d1 are not 90 ° phase shifted, and/or d1 and d2 are not 90 ° phase shifted, the sensor device may output the correct angular position θ 2oc and may mark that an error has occurred, in particular H1 may be defective in this example.

Similarly, if it is found (in any angular position) that d3 and d4 are 90 ° phase shifted, while d1 and d2 are not 90 ° phase shifted, and/or d2 and d3 are not 90 ° phase shifted, and/or d4 and d1 are not 90 ° phase shifted, the sensor device may output the correct angular position θ 4oc and may mark that an error has occurred, especially in this example H2 may be defective.

Similarly, if it is found (in any angular position) that d4 and d1 are 90 ° phase shifted, while d1 and d2 are not 90 ° phase shifted, and/or d2 and d3 are not 90 ° phase shifted, and/or d3 and d4 are not 90 ° phase shifted, the sensor device may output the correct angular position θ 3oc and may mark that an error has occurred, in particular H3 may be defective in this example.

In the case where no error is found, for example, if d1 and d2 are found to be phase shifted by 90 °, d2 and d3 are found to be phase shifted by 90 °, d3 and d4 are found to be phase shifted by 90 °, and d4 and d1 are found to be phase shifted by 90 °, the apparatus may output any one of the offset compensation angles as the angular position, or output a combination thereof (e.g., an average or a median). In this case, an angular value calculated using the diameter difference as shown in fig. 1 (c) may also be output.

Thus, the calculation of four angles as described above and shown in fig. 3 (b) may be used for error detection and, in case of an error being detected, instead of providing an incorrect value based on the diameter difference (as is the case in the sensor device of fig. 1 (c)), the correct angle value is provided based on only three signals. It should be clear that such a sensor device may be ideally used for "functional safety purposes".

In another variant, also shown in fig. 3 (a), the sensor device comprises four horizontal hall elements H1, H2, H3, H4 located on an imaginary circle and angularly spaced apart by multiples of 90 °. The sensor device further comprises a processing unit connected to the four hall elements and configured for:

i) Calculating two "neighboring differences", e.g., d1 and d2 of fig. 3 (b), or d2 and d3 of fig. 3 (b), or d3 and d4 of fig. 3 (b), or d4 and d1 of fig. 3 (b); and

ii) optionally calculating a "first angle" as a function of these neighboring differences, e.g. resulting in any of the angles θ 1 to θ 4 in fig. 3 (b); and

iii) Calculating two "diagonal differences", e.g., d1 and d2 in FIG. 1 (c); and

iv) optionally calculating a "second angle" as a function of the diagonal differences, e.g. as the arctangent of the ratio of the differences.

The sensor device may be further configured to output one or both of two "adjacent differences" and/or "first angles"; and for outputting one or both of "two diagonal differences" and/or "second angles". The consistency check may be performed inside the sensor device or outside the sensor device (e.g. in the ECU).

In a particular embodiment, the sensor device is configured for calculating and outputting a "first angle" (derived from two adjacent differences) and for calculating and outputting a "second angle" (derived from two diagonal differences) to allow an external processor to perform a consistency check (e.g. by comparing the two angles).

In a particular embodiment, the sensor device is configured for calculating and outputting a "second angle" (derived from two diagonal differences), and for calculating and outputting two adjacent differences (e.g. d1 and d2 as defined in fig. 3 (b)), for allowing the external processor to calculate the "first angle" and perform the consistency check.

In a particular embodiment, the sensor device is configured for calculating and outputting a "first angle" (derived from two adjacent differences) and for calculating and outputting a "second angle" (derived from two diagonal differences) and for performing a consistency check (e.g. by comparing the two angles) and for outputting at least one of said angles and for outputting a result of the consistency check.

Fig. 4 (a) shows a magnetic sensor device 420 as a variation of the sensor device of fig. 2 (e). The sensor device 420 has a first set (or set) of three horizontal hall elements H1, H2, H3 and is configured to calculate the difference d1= (H1-H2) and the second difference d2= (H2-H3) and the first angle from θ 1=atan2[ (H1-H2), (H2-H3) ] in the same manner as described in fig. 2 (a) to 2 (c). However, in addition to H1 to H3, the sensor device 420 has a second group (or set) of three horizontal hall elements H4, H5, H6 and is configured for calculating a second angle θ 2 (e.g. according to θ 2= atan2[ (H4-H5), (H5-H6) ]) based on the pair-wise differences d3= (H4-H5) and d4= (H5-H6). The second angle may be offset compensated by adding or subtracting a predefined value (e.g., 180 ° for the topology of fig. 4 (a)). The sensor device 420 may be further configured to compare the offset compensation angles θ 1 and (θ 2-180 °) and detect an error based on the comparison, e.g. to determine that an error has occurred if the two values θ 1 and (θ 2-180 °) deviate by more than a predefined value. In case no error is detected, the first angle θ 1, or the offset compensated second angle (θ 2-180 °), or the average of these angles may be output.

As described above, the offset compensation and/or consistency check may be performed external to the sensor device 420, for example in a digital controller connected to the sensor device 420. In this case, the sensor device will provide both θ 1 and θ 2, or both θ 1 and the offset compensated second angle, to allow for external comparison.

Alternatively or additionally, one or more angles may also be calculated based on the diagonal difference. In one such example, signals h1, h2, h3, and h5 are used, but h4 and h6 are not used, e.g., as follows: θ 3= atan2 (h 1-h3, h2-h 5). In another example, signals h6, h2, h4, and h5 are used, but h1 and h3 are not used, e.g., as follows: θ 4= atan2 (h 6-h4, h2-h 5). A combination of h1 and h6 (e.g., parallel or sum or average), and/or a combination of h3 and h4 (e.g., parallel or sum or average) may also be used, for example, as follows: θ 5= atan2[ (h 1+ h6-h3-h 4), 2 × (h 2-h 5) ].

Fig. 4 (b) shows the example or variation of fig. 4 (a), illustrating an arrangement of six sensor elements H1 to H6, wherein the elements H1, H2, H3 of the first group are spaced apart by 90 °, and wherein the elements H4, H5, H6 of the second group are spaced apart by less than 90 ° (e.g. by an angle in the range of 80 ° to 89 °). In the figure, the angle α 1 between H4 and H5 (seen from the center) is about 80 °, but the figure is not drawn to scale. In a practical implementation, the imaginary circle may have a radius in the range of 0.5mm to 1.5mm, e.g., equal to about 1.0mm, and the size of the Hall plate may be about (20 microns) ² And angle α 1 can be very close to 89A value, for example, in the range of 85 ° to 89 ° or in the range of 87 ° to 89 °. The same applies to the angle α 2 (viewed from the center) between H5 and H6. The sensor elements H2 and H5 can be located exactly diametrically opposite one another. The sensor apparatus of fig. 4 (b) may be configured to calculate the first angle θ 1 as atan2 (h 1-h2, h2-h 3), the second angle θ 2 as atan2 (h 4-h5, h5-h 6), and calculate the offset-compensated second angle value θ 2oc according to the following formula: θ 2oc = θ 2-180 °, and may be further configured to compare the values of θ 1 and θ 2oc, conclude that the measured values are correct if the difference of these values does not exceed a certain threshold, and determine that an error is detected if the difference of these values does exceed the threshold. The threshold may be a predefined constant value (e.g. a value of 5 ° or 3 °), or may depend on the value θ 1 (e.g. 3 ° if θ 1 is within the first sub-range, 5 ° if θ 1 is within the second sub-range). It is noted that the angle θ 2oc may deviate slightly from the angle θ 1, since the elements H4, H5, H6 in fig. 4 (b) are not exactly 90 ° apart, but this is fully acceptable for functional safety purposes.

In case no error is detected, the sensor device may output an average value of θ 1 or θ 2oc or θ 1 and θ 2oc, or a value based on the diameter difference signals (h 2-h 5) and (h 1-h 3).

In the event that an error is detected, the sensor device may be configured to determine which signal is incorrect, for example by using hall elements H1, H2, H3 and H5 in the same manner as described in fig. 3 (b). After determining which sensor signal is incorrect, the angular position is determined using the other three sensor elements. For example, in the case where the signal H1 is found to be incorrect, the angular position may be calculated based on signals obtained from H2, H3, and H5.

In a variant, one or both of the angles α 1 and α 2 may be slightly greater than 90 °, for example a value in the range 91 ° to 100 ° or a value in the range 91 ° to 95 °. The same effects and advantages apply in this case.

Fig. 4 (c) shows another illustrative arrangement of six sensor elements H1 to H6, wherein the elements H1, H2, H3 of the first group are spaced apart from each other by a multiple of 90 °, and wherein the elements H4, H5, H6 of the second group are spaced apart from each other by 90 °, but wherein the elements H2 and H5 are not located or not located exactly on opposite sides of the imaginary circle, and none of the elements of the first group coincide with an element of the second group. The sensor device is also capable of determining the first angle θ 1 and the second angle θ 2, and determining whether an error has occurred based on these values.

Fig. 4 (d) shows an example of a semiconductor substrate comprising two sets of three horizontal hall elements, similar to the arrangement of fig. 4 (c), but a more compact arrangement can be obtained by positioning H4 close to H1, H5 close to H2 and H6 close to H3. In this embodiment "close" means that the distance between the centers of the sensor elements is less than 250 μm, or less than 200 μm, or less than 100 μm, or less than 50 μm. Preferably, the six hall elements are located over an arc length of less than 220 °, or less than 210 °, or less than 200 °, or less than 190 °. The sensor device of fig. 4 (d) has the same advantages as fig. 4 (c).

In case no error is detected, it is also possible to combine the signals of H1 and H4, the signals of H2 and H5 and the signals of H3 and H6 (for example by connecting these hall elements in parallel or in series in the analog domain, or by averaging or summing the signals in the digital domain) and calculate the angle based on the pairwise combined signals, for example as θ 3= atan2 (H1 + H4-H2-H5, H2+ H5-H3-H6). The angular position may have an improved signal-to-noise ratio (SNR). In an embodiment, the Hall elements H1 and H4, H2 and H5, and H3 and H6 may be positioned "very close together," e.g., less than 100 μm, or less than 75 μm, or less than 50 μm.

Fig. 4 (e) shows a sensor device using the same sensor topology as shown in fig. 4 (a), but wherein the sensor device contains two functionally separate circuits, each comprising a set of three hall elements, biasing circuitry and readout circuitry, and optionally a separate analog-to-digital converter and/or digital processing circuit. This will be discussed further in fig. 7 to 9 (c).

In a variant of fig. 4 (a) (not shown), two additional horizontal hall elements are added: h7 adjacent or contiguous to H2, and H8 adjacent or contiguous to H5. The eight sensor elements H1 to H8 may be arranged in four pairs, each pair being angularly spaced by about 90 °, and the centers of the two hall elements within each pair being positioned at a distance of less than 100 μm or less than 75 μm or less than 50 μm. Considering that the size of each hall element is relatively small (e.g., about 20 μm × 20 μm or about 25 μm × 25 μm) and the diameter of the imaginary circle is relatively large (e.g., about 1000 μm to 3000 μm), it can be understood that each pair of hall elements measures substantially the same value. The sensor device may implement one or more of the following modes:

i) Calculating four angles using a combination of only three sensors selected from H1 to H4, and/or detecting an error or problem in any one of H1 to H4 in a manner similar to fig. 3 (b), and/or calculating angles based on the difference in diameters as in fig. 1 (c) using H1 to H4;

ii) four angles are calculated using a combination of only three sensors selected from H5 to H8, and/or an error or problem of any one of H5 to H8 is detected in a manner similar to fig. 3 (b), and/or angles are calculated based on the difference in diameters as in fig. 1 (c) using H5 to H8;

iii) Calculating an angle based on a diameter difference of the pair-wise combined signals (h 1+ h 5), (h 2+ h 6), (h 3+ h 7), and (h 4+ h 8);

iv) combining the signals of each sensor pair and calculating four angles using a combination of only three sensor pair signals; and/or to detect errors or problems in any of these pairs in a manner similar to fig. 3 (b), and/or to calculate an angle based on the diameter difference as in fig. 1 (c) using the sensor pair signals.

The main advantage of such an embodiment with eight sensor elements is that the device is able to determine which of the individual hall elements H1 to H8 is defective and/or which pair is defective and to provide a correct angular position to provide an angle based on the difference in diameter between the pair-wise combinations even in case of one defective element/one defective pair and in case no error is found, which provides a highly reliable value with an improved signal-to-noise ratio (SNR).

Fig. 5 (a) shows a magnetic sensor device that is a variation of the device of fig. 4 (a) to 4 (c), also having two sets of three hall elements, and capable of determining a first angle using a first subset H1, H2, H3 of the three hall elements and a second angle using a second subset of the three hall elements H4, H5, H6 independent of the first subset (e.g., according to the formulas θ 1= atan2 (H1-H2, H2-H3) and θ 2= atan2 (H4-H5, H5-H6)).

The main difference between the sensor device of fig. 5 (a) and the sensor devices of fig. 4 (a) to 4 (c) is that the first set of three hall elements H1, H2, H3 is located on a first circle having a first radius R1, while the second set of three hall elements H4, H5, H6 is located on a second circle having a different second radius R2 (e.g. the second radius R2 is smaller than the first radius R1). The first circle and the second circle are concentric circles, i.e. they have the same center. An advantage of using two different radii is that the hall elements of each subset can be angularly spaced exactly 90 °.

In the example shown in fig. 5 (a), four sensor elements H1, H3, H4, H6 are collinear. This provides a further advantage that the sensor device can perform additional checks, since ideally the difference signal (h 1-h 3) should be proportional to the difference signal (h 6-h 4) using a predefined constant, which can be determined during design or can be measured during calibration and stored in a non-volatile memory of the sensor device. If the result is that (h 1-h 3) is not proportional to (h 6-h 4), an error is detected. This can be written as: (h 1-h 3) = a (h 6-h 4), wherein a is a constant.

Another advantage of the arrangement of fig. 5 (a) is that the virtual line segment connecting the hall elements H2 and H5 is perpendicular to the virtual line segment connecting H1 and H3. The third angle may be determined as θ 3= atan2 (h 1-h4, h2-h 5), and/or the fourth angle may be determined as θ 4= atan2 (h 6-h3, h2-h 5), and/or the fifth angle may be determined as θ 5= atan2[ (h 1-h 3), B × (h 2-h 5) ], and/or the sixth angle may be determined as θ 6= atan2[ (h 6-h 4), C: (h 2-h 5) ], where B and C are predefined constants, which may be determined during design, or may be measured during calibration tests. All these angles θ 1, (θ 2-180 °), θ 3, θ 4, θ 5, θ 6 should yield substantially the same values (within certain tolerances, e.g. within tolerances of at most ± 3 ° or at most ± 2 °). Thus, errors can be detected by comparing these values and in a similar manner as above, it is also possible to detect which element is defective in case of an error or malfunction. If no error is detected, the sensor device may provide one or more of these angles as its output, or an average of two or more of these angles. In case an error is detected, the correct angular position can be provided without using a faulty element.

Note that in case R2 is only slightly smaller than R1, e.g. if (R1-R2) is smaller than 100 μm or smaller than 75 μm, or smaller than 50 μm, the values of h1 and h6 should be very similar, and likewise the values of h4 and h3 should be very similar, and the sensor device may be configured to verify that these signals deviate less than a predefined amount. Also in this case, the values of h1 and h6 may be averaged, and the values of h3 and h4 may be averaged, and the angular position may be calculated from θ 7= atan2[ (h 1+ h6-h3-h 4), D (h 2-h 5) ], where D is a predefined constant or determined during calibration. Preferably, D is a value in the range of 1.9 to 2.1. This angular value may be less sensitive to manufacturing tolerances.

In summary, the sensor device of fig. 5 (a) is not only able to determine an angle, but is also able to detect an error, and is able to provide a correct angle even in the presence of an error, and therefore also has error correction capability.

Fig. 5 (b) shows a variant of the semiconductor substrate of fig. 5 (a), also having three sensor elements H1 to H3 located on a first circle having a radius R1 and angularly spaced apart by a multiple of 90 °, and three sensor elements H4 to H6 located on a second circle having a radius R2 and angularly spaced apart by a multiple of 90 °, and wherein H1, H3, H4 and H6 are located on an imaginary straight line, but wherein sensor elements H2 and H5 are located on the same side of said imaginary straight line, or in other words wherein sensor elements H1 and H4 are arranged "closely together", and wherein sensor elements H2 and H5 are arranged "closely together", and wherein sensor elements H3 and H6 are arranged "closely together", preferably at a distance of at most 100 μm or at most 75 μm or at most 50 μm. This sensor device provides some of the same advantages as mentioned in fig. 5 (a), in particular in that it allows to determine θ 1 and θ 2 and detect errors, and in case no errors are detected, the values of h1 and h4, h2 and h5, h3 and h6 can be averaged, and it even allows to determine which sensor element is defective, because the values of h2, h5 should be shifted substantially 90 ° with respect to the values of h1, h4, and because the values of h3, h6 should be shifted substantially 90 ° with respect to the values of h2, h5, which can be tested. It does not allow the angle to be calculated based on the difference in diameter because H5 is not located diametrically opposite H2.

Other variations of fig. 5 (a) are also contemplated having eight hall elements, H1-H4 lying on a first circle having a first radius R1, and H5-H8 lying on a second circle having a second radius R2. This embodiment provides the same advantages as the above-described variant of fig. 4 (a) with eight hall elements, but provides the additional advantage that the sensor elements H5 to H8 are spaced exactly 90 ° apart. The four modes i) to iv) described above are also possible here.

FIG. 6 shows an electrical block diagram of circuitry 610 that may be used in the position sensor apparatus described above. The circuit 610 includes a plurality of magnetic sensor elements and includes a processing unit 630 and a non-volatile memory 631.

The plurality of magnetic sensor elements may comprise: (i) A single set of only three horizontal hall elements H1, H2, H3, e.g. as shown in fig. 2 (a) to 2 (f); or (ii) a single set of four horizontal hall elements H1, H2, H3, H4, e.g. as shown in fig. 3 (a) and 3 (b); or (iii) only three horizontal hall elements (H1, H2, H3) and (H4, H5, H6) of the two sets, for example as shown in fig. 4 (a) to 5 (b), or (iv) four horizontal hall elements of the two sets.

The processing unit 630 is adapted to determine the position (e.g. angular position θ) in a manner as described above, for example by using a mathematical formula or a look-up table, optionally using interpolation. As described above, the position is based on the ratio of the difference signals. The subtraction can be done in the analog domain before or after amplification, or in the digital domain.

The processing unit 630 may include a digital processor, which may optionally include or be connected to non-volatile memory 631. The memory may be configured to store one or more constants. The digital processor may be, for example, an 8-bit processor or a 16-bit processor.

Although not explicitly shown, the processing circuitry may include one or more components or sub-circuits selected from the group consisting of: amplifiers, differential amplifiers, analog-to-digital converters (ADCs), and the like. The ADC may have a resolution of at least 8 bits or at least 10 bits or at least 12 bits or at least 14 bits or at least 16 bits.

The processing circuit 630 may, for example, use I via a digital interface (e.g., a serial bus interface), for example ² The C protocol provides the position as an analog or digital signal, either using the RS232 protocol or any other suitable protocol.

Optionally, the processing unit 630 is further configured for providing one or more of the above mentioned difference signals (h 1-h 2), (h 2-h 3), (h 3-h 1) to an external processor (not shown), e.g. an Electronic Control Unit (ECU), in an analog or digital format via the same interface or via another interface (not shown), e.g. to allow the external processor to check the data.

Optionally, the processing unit 630 is further configured to provide a control signal (or consistency signal), labeled "error" in fig. 6, to indicate whether an error is detected, or to indicate that no error is detected, or to indicate that an error is detected and corrected.

FIG. 7 shows an electrical block diagram of a circuit 710 that may be used with the position sensor apparatus described above, the circuit 710 having two sets of Hall elements. This circuit 710 is a variation of the circuit 610 of fig. 6. In this circuit, the signals h1 to h6 of the two sets of sensor elements are provided to a processing unit 730, the processing unit 730 being configured for determining the angular position of the magnet relative to the sensor device (or vice versa) in the manner as explained above, and for providing a control signal, for example an "error", to indicate that an error is detected, or to indicate that no error is detected, or to indicate that an error is detected and corrected. Optionally, the processing unit 730 is further configured to provide one or more of the above mentioned difference signals or averaged signals to an external processor (not shown), e.g. an Electronic Control Unit (ECU), in an analog or digital format via the same interface or via another interface (not shown), e.g. to allow the external processor to check the data.

In an alternative embodiment, the magnetic sensor device is configured for providing the two angular values (e.g. θ 1, θ 2) to another processor (e.g. ECU), and the latter is configured for comparing the two angular values to detect an error. In this case, the error output may be ignored.

In a variant of fig. 7 (not shown), the first set "set 1" contains four hall elements H1 to H4, the second set "set 2" also contains four hall elements H5 to H8, and the processing unit may be configured to operate in any of the modes i) to iv) described above, or may be configured to perform at least two of these modes, for example i) and ii), or i) and ii) and iii).

Fig. 8 shows a variation of the electrical block diagram of fig. 7, wherein the first set of hall elements H1-H3 have dedicated bias and readout circuits (not shown) and dedicated processing circuits 830 (e.g., including ADCs, amplifiers, digital processors, or shift registers), and wherein the second set of hall elements H4-H6 have dedicated bias and readout circuits (not shown) and dedicated processing circuits 832 (including, for example, ADCs, amplifiers, digital processors, or shift registers), separate and independent from the first processing circuits 830. As suggested in fig. 4 (e), the two partial circuits may optionally be galvanically separated and may have dedicated pads.

As explained above, the circuits of fig. 7 and 8 are well suited for applications where "functional safety" is important, but these are not the only possible implementations.

Fig. 9 (a) shows a block diagram of a readout circuit comprising a multiplexer MUX, a single analog-to-digital converter ADC and a single digital processor DSP. This block diagram can be used in the circuit of fig. 7 and its main purpose is to detect errors related to the hall element (transducer) and its biasing and readout circuitry.

Fig. 9 (c) shows a block diagram of two completely independent readout circuits, each comprising an analog-to-digital converter ADC and a digital processor DSP. This block diagram can be used in the circuit of fig. 8 and is intended to provide full redundancy.

Fig. 9 (b) shows a block diagram of another solution, which can be considered an "intermediate solution", having a multiplexer and a single ADC, and a circuit that sends the digitized values from the first set of hall elements to the DSP for further processing, but not to the DSP, but to an output (e.g., to the same output in a time-multiplexed manner), or to a second output different from the first output. These digital values may be further processed externally (e.g., in another processor, such as in the ECU). Of course, however, many variations are possible, for example, the sensor device may calculate the pairwise differences (h 4-h 5), (h 5-h 6), (h 6-h 4) and output them to an external processor instead of outputting digitized versions of the sensor signals h4, h5, h 6. Where the sensor device comprises 8 sensor elements, the sensor device may be further configured to output a pair-wise combination (h 1+ h 5), (h 2+ h 6), (h 3+ h 7) and/or a "neighboring difference" of some or all of these pairs, and/or a "diagonal difference" of some or all of these pairs.

Finally, in a preferred embodiment of the invention, the sensor device does not contain a vertical hall element, does not contain an integrated flux concentrator (also referred to as "IMC"), and does not contain a magnetoresistive element (such as an MR element).

In a preferred embodiment of the invention, the sensor device does not contain ferromagnetic material. This provides the advantage that the magnetic field lines are not (or not significantly) curved and thus the magnetic field can be measured with minimal effect.

In a preferred embodiment of the invention, the diameter of the imaginary circle is a value in the range of 1.0mm to 3.0mm, or a value in the range of 1.5mm to 2.5 mm. The outer diameter of the ring or disc magnet is typically in the range of 3.0mm to 20.0mm, or in the range of 4mm to 20 mm. The ratio between the diameter of the imaginary circle (or the largest imaginary circle) on which at least some of the sensor elements are located and the outer diameter of the ring or disc magnet is typically in the range of 2 to 10, 2 to 6, 4 to 8 or 6 to 10.

Claims (17)

1. An angular position sensor system comprising:

a bipolar magnet rotatable about a rotation axis (A);

a magnetic sensor device comprising a plurality of horizontal hall elements including at least a first, a second and a third horizontal hall element (H1, H2, H3) located on a virtual circle, said circle having a center located on said rotation axis (a);

wherein the first and second horizontal Hall elements (H1, H2) are angularly spaced by 90 °, and wherein the first and third horizontal Hall elements (H1, H3) are angularly spaced by 180 °.

Wherein the magnetic sensor device further comprises a processing unit connected to the first, second and third horizontal hall elements for obtaining first, second and third signals (h 1, h2, h 3) and configured for determining a first pair-wise difference (d 1) between the first and second sensor signals (h 1, h 2) and for determining a second pair-wise difference (d 2) between the second and third sensor signals (h 2, h 3) and for determining an angular position (θ) of the magnetic sensor device relative to the magnet based on a ratio of the first and second pair-wise differences (d 1, d 2).

2. The angular position sensor system of claim 1,

wherein the imaginary circle has a radius (R1);

and wherein the horizontal hall element is integrated on a single semiconductor substrate having an area smaller than four times the square of the radius (R1).

3. The angular position sensor system of claim 1,

wherein the sensor device comprises only three horizontal hall elements.

4. The angular position sensor system of claim 1,

wherein the plurality of horizontal hall elements further comprises a fourth horizontal hall element (H4) located on the imaginary circle, and the fourth horizontal hall element (H4) is spaced 180 ° apart from the second horizontal hall element (H2), and wherein the processing unit is further connected to the fourth horizontal hall element (H4) to receive a fourth sensor signal (H4); and is provided with

Wherein the processing unit is further configured for one or more or all of:

i) -determining a third pair-wise difference (d 3) between the third sensor signal (h 3) and the fourth sensor signal (h 4), and for determining a second angle (θ 2) of the magnetic sensor device based on a ratio of the second pair-wise difference (d 2) and the third pair-wise difference (d 3);

ii) determining a third pair-wise difference (d 3) between the third sensor signal (h 3) and the fourth sensor signal (h 4) and determining a fourth pair-wise difference (d 4) between the first sensor signal (h 1) and the fourth sensor signal (h 4) and for determining a third angle (θ 3) of the magnetic sensor device based on a ratio of the third pair-wise difference (d 3) and the fourth pair-wise difference (d 4) or for determining a third angle (θ 3) of the magnetic sensor device based on a ratio of the third pair-wise difference (d 3) and the fourth pair-wise difference (d 4)

iii) -determining a fourth pair-wise difference (d 4) between the first sensor signal (h 1) and the fourth sensor signal (h 4), and-determining a fourth angle (θ 4) of the magnetic sensor device based on a ratio of the fourth pair-wise difference (d 4) and the first pair-wise difference (d 1).

5. The angular position sensor system of claim 4,

wherein the processing unit is further configured for determining a first diagonal difference (dd 1) as the difference between the first signal (h 1) and the third signal (h 3), and for determining a second diagonal difference (dd 2) as the difference between the second signal (h 2) and the fourth signal (h 4), and for determining a fifth angle (θ 5) of the magnetic sensor device based on the ratio of these diagonal differences (dd 1, dd 2).

6. The angular position sensor system of claim 1,

wherein the plurality of horizontal Hall elements further comprises a fourth horizontal Hall element, a fifth horizontal Hall element and a sixth horizontal Hall element (H4, H5, H6) located on a second virtual circle having a second center located on the rotation axis (A);

and wherein the processing unit is further connected to the fourth, fifth and sixth horizontal hall elements (H4, H5, H6) and is further configured for receiving fourth, fifth and sixth sensor signals (H4, H5, H6);

and wherein the processing unit is further configured to determine a first additional pair-wise difference (aidif 1) between the fourth and fifth sensor signals (h 4, h 5), and to determine a second additional pair-wise difference (aidif 2) between the fifth and sixth sensor signals (h 5, h 6), and to determine an additional angle (ψ) of the magnetic sensor device relative to the magnet based on a ratio of the first additional pair-wise difference (aidif 1) and the second additional pair-wise difference (aidif 2).

7. The angular position sensor system of claim 6,

wherein the fourth and fifth horizontal Hall elements (H4, H5) are angularly spaced apart (α 1) by an angle in the range of 80 ° to 89 ° or 91 ° to 100 °, and wherein the fifth and sixth horizontal Hall elements (H5, H6) are angularly spaced apart (α 2) by an angle in the range of 80 ° to 89 ° or 91 ° to 100 °.

8. The angular position sensor system of claim 6,

wherein the fourth and fifth horizontal Hall elements (H4, H5) are spaced apart by 90 ° (α 1), and wherein the fifth and sixth horizontal Hall elements (H5, H6) are also spaced apart by 90 ° (α 2).

9. The angular position sensor system of claim 6,

wherein the first virtual circle has a first radius (R1), and wherein the second virtual circle has a second radius (R2) that is smaller than the first radius (R1); and is

Wherein the first, third, fourth and sixth horizontal Hall elements (H1, H3, H4, H6) are collinear.

10. The angular position sensor system of claim 6,

wherein the first virtual circle has a first radius (R1), and wherein the second virtual circle has a second radius (R2) equal to or smaller than the first radius (R1);

and wherein the distance between the center of the first hall element (H1) and the center of the fourth hall element (H4) is less than 250 μ ι η; and wherein the distance between the center of the second hall element (H2) and the center of the fifth hall element (H5) is less than 250 μm; and wherein the distance between the center of the third hall element (H3) and the center of the sixth hall element (H6) is less than 250 μm.

11. The angular position sensor system of claim 1,

wherein the semiconductor substrate has an area in a range of 51% to 98% of 4 (R1),

wherein R1 is a radius of the first imaginary circle.

12. The angular position sensor system of claim 4,

wherein the processor unit is configured for outputting at least two angular values (θ 1, θ 2);

and wherein the system further comprises an Electronic Control Unit (ECU) communicatively connected to the magnetic sensor device and configured for receiving the at least two angular values and further configured for detecting an error based on a comparison of the first and second angular values (θ 1, θ 2).

13. The angular position sensor system of claim 4,

wherein the processor unit is configured for outputting at least a first angular value (θ 1) and at least two difference signals;

and wherein the system further comprises an Electronic Control Unit (ECU) communicatively connected to the magnetic sensor device;

and wherein the Electronic Control Unit (ECU) is configured for receiving the first angular value (θ 1) and the at least two difference values, and further configured for calculating a second angular value (θ 2) based on these difference values, and for detecting an error based on a comparison of the first and second angular values (θ 1, θ 2).

14. The angular position sensor system of claim 1,

wherein the plurality of horizontal hall elements further comprises a fourth horizontal hall element (H4) located on the imaginary circle, and the fourth horizontal hall element (H4) is spaced 180 ° apart from the second horizontal hall element (H2), and wherein the processing unit is further connected to the fourth horizontal hall element (H4) to receive a fourth sensor signal (H4);

and wherein the processing unit is further configured for determining a first diagonal difference (dd 1) as the difference between the first signal (h 1) and the third signal (h 3) and for determining a second diagonal difference (dd 2) as the difference between the second signal (h 2) and the fourth signal (h 4) and optionally for determining a second angle (θ 5) of the magnetic sensor device based on the ratio of these diagonal differences (dd 1, dd 2);

and wherein the sensor device is further configured for outputting the angular position (θ) derived from the first, second and third horizontal hall elements (h 1, h2, h 3) as a first angle, and for outputting at least one of the first and second diagonal differences (dd 1, dd 2) and the second angle (θ 5).

15. The angular position sensor system of claim 14,

wherein the sensor device is configured for determining the second angle (θ 5), and for performing a conformance test between the first angle (θ) and the second angle (θ 5), and for outputting a result of the conformance test.

16. The angular position sensor system of claim 14,

wherein the system further comprises an Electronic Control Unit (ECU) communicatively connected to the magnetic sensor device;

and wherein the Electronic Control Unit (ECU) is configured for receiving the first and second angular values (θ, θ 5) and for detecting an error based on a comparison of the first and second angular values (θ, θ 5).

17. The angular position sensor system of claim 14,

wherein the system further comprises an Electronic Control Unit (ECU) communicatively connected to the magnetic sensor device;

and wherein the Electronic Control Unit (ECU) is configured for receiving the first angular value (θ), and for receiving the first and second diagonal differences (dd 1, dd 2), and for calculating the second angle (θ 5) based on the first and second diagonal differences, and for detecting an error based on a comparison of the first and second angular values (θ, θ 5).

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